The role of T cells in influenza infection and vaccination

Influenza virus infections cause significant illness or death every year, becoming a serious health risk. Currently, influenza vaccines mainly induce responses to antibodies against specific strains, but they do not effectively induce effective T cell-mediated immunity. Humoral immunity relies on the production of antibodies that bind to surface proteins (such as hemagglutinin and neuraminidase) to combat the virus. These antibodies envelope the virus to prevent it from invading cells and also label the virus for phagocytic cells to clear. T cell-mediated immunity relies on cytotoxic cells to kill infected cells to combat the virus. Cytotoxic T cells rely on viral proteins on the surface of infected cell to recognize them. This enables the detection of more viral proteins, such as internal proteins like nucleoproteins. A better understanding of the mechanism by which T cells combat influenza is helpful for vaccine development. In this review, we elaborate on the role of T cells in enhancing anti-influenza immune defense. In addition, we explore the possibility that new influenza vaccines can induce such T cell responses.